Shangdu, the Upper Capital of Kublai Khan

Listen first. Wind moves through the grass here with a low, steady hiss. Larks call overhead. Underfoot, the ground is soft and uneven, and long green ridges cross the plain in straight lines. Those ridges are not natural. They are the remains of city walls, made of rammed earth and slowly covered by turf. You are standing inside what was once one of the most talked-about cities on Earth.

This is Shangdu, the Upper Capital. In the West it has another name, one you may already know: Xanadu. It lies on the open grassland of Inner Mongolia, a short drive from the town of Duolun. Today it looks quiet and almost empty. But in the thirteenth century, this was the summer seat of the Mongol emperors. Envoys, monks, merchants and soldiers came here from across Asia.

The story begins in 1256. Kublai, a grandson of Genghis Khan, was then a prince. He ordered a new city built on these grasslands. His trusted adviser Liu Bingzhong, a Chinese scholar and former Buddhist monk, planned the site. At first it was called Kaiping. A few years later, in 1260, Kublai was proclaimed Great Khan, and his rise to power was tied closely to this place.

In 1263 the city received the name Shangdu. Later, Kublai built a second capital far to the south, on the site of present-day Beijing. That city became the winter capital. So each year the imperial court moved between the two. Winter was spent in the south. Summer was spent here, where the air is cooler and the pastures are wide. It was a Mongol way of life, given the form of an empire.

Now look at the layout around you. Shangdu was built as three cities, one inside another. At the centre stood the Palace City, where the emperor lived. Around it was the Imperial City, with offices, temples and homes for officials. Wrapped around both was the Outer City, with gardens, hunting grounds and more quarters. As you walk, you can trace these rings in the grassy lines of the old walls.

Here is the first thing many visitors miss. Shangdu is not purely Chinese, and not purely Mongol. It is a blend of both. The planners used Chinese ideas about city design and the position of mountains and water. A range of hills rises to the north. The river runs to the south. But inside the walls, there was space for tents, horses and open ground. Steppe life and Chinese city planning lived side by side here.

That river, by the way, is the Shandian, the upper course of the Luan River. Look south across the plain and you may see its line of wetland and willows. The river fed marshes that drew birds and game. For the Mongol court, hunting was more than sport. It was a way to train riders and show power. The grasslands around the city served as a royal hunting reserve.

The Venetian traveller Marco Polo described the city in his famous book. He wrote of a great marble palace, rooms decorated with gold, and a large walled park full of animals. He also described a movable palace made of cane, held up by silk cords, that could be taken apart. Historians still debate how much of his account he saw himself. But his words carried the name of this place to Europe.

Polo also described a summer ritual. According to his account, the emperor scattered mare's milk across the ground as an offering to the spirits. Fermented mare's milk was, and still is, an important drink on the steppe. Whether every detail of his story is exact, the ritual fits Mongol tradition. It reminds us that this court never forgot its roots in herding life.

And here is the second surprise. Centuries later, in 1797, the English poet Samuel Taylor Coleridge wrote a poem called Kubla Khan. It begins with the famous line: In Xanadu did Kubla Khan a stately pleasure-dome decree. Coleridge said the poem came to him in a dream, after reading about this city. So a ruin on the Mongolian grassland gave the English language a word for any place of dreamlike splendour.

The city's glory did not last. The Mongol Yuan dynasty grew weak in the fourteenth century. Rebel armies attacked and burned Shangdu during the uprisings that ended Mongol rule in China. After the new Ming dynasty took power, the city was abandoned. Wooden halls rotted or burned. Bricks and stones were carried away. Slowly, the grass returned and covered almost everything you see today.

Yet that slow burial is also what kept Shangdu so clear on the ground. No modern city was built on top of it. The plan of streets, gates and building platforms remains easy to read. Archaeologists have studied the foundations of palaces and halls here. In 2012, the site was added to the UNESCO World Heritage List, recognised as a rare meeting point of steppe and settled cultures.

Take a moment before you go. Turn slowly in a full circle. Notice how the earthen walls run straight to the horizon, then soften into the grass. Watch the cloud shadows pass across the plain. Somewhere beneath your feet are the floors of halls where an emperor once received the world. As you walk back, listen again to the wind. It is the same wind the court felt every summer, more than seven centuries ago.